UP2.2 | Exploring the interfaces between meteorology and hydrology
Exploring the interfaces between meteorology and hydrology
Conveners: Timothy Hewson, Fatima Pillosu | Co-conveners: Stefan Kollet, Jan-Peter Schulz
| Wed, 06 Sep, 14:00–15:30 (CEST)|Lecture room B1.04
| Attendance Thu, 07 Sep, 16:00–17:15 (CEST) | Display Wed, 06 Sep, 10:00–Fri, 08 Sep, 13:00|Poster area 'Day room'
Orals |
Wed, 14:00
Thu, 16:00
Meteorology and hydrology act in tandem across the interface of the earth's surface. Such an interface will become increasingly important as our understanding and predictive capabilities improve. For the good of society, the need to meld together the two disciplines is now more vital than ever. Many national meteorological services worldwide have, formally or informally, evolved into national hydro-meteorological services. The session, introduced in 2019, aims to provide an all-embracing hydro-meteorological forum where experts from both disciplines can combine and exploit their expertise to accelerate the integration of these two fields. We invite contributions across a wide range of spatial scales (from 10s of meters up to global) and a wide range of time scales (from ~1 hour up to seasonal and climate change), including, but not limited to, the following topics: land-atmosphere interactions and hydrological processes, including feedback mechanisms; understanding the meteorological processes driving hydrological extremes; tools, techniques, and expertise in forecasting hydro-meteorological extremes (e.g., river flooding, flash floods, etc.); the role of the vegetation in this context, in terms of transpiration, photosynthesis, phenology, etc.; energy cycles, complementing the hydrological cycles and related cryospheric processes; fully integrated numerical earth system modelling; quantification/propagation of uncertainties in hydro-meteorological models; quantification of (past/future) hydrological trends in observations and climate models; hydro-meteorological prediction that includes the associated impacts; environmental variable monitoring by remote sensing and other observations; droughts (in tandem with the 2023 conference theme).

Orals: Wed, 6 Sep | Lecture room B1.04

Chairpersons: Timothy Hewson, Jan-Peter Schulz
Onsite presentation
Woon Mi Kim, Santos J. González-Rojí, and Isla Simpson

Understanding the drivers of droughts is essential to improve the prediction of these extreme events and develop potential early warning systems and mitigation strategies. Until now, many studies have examined general relationships between precipitation, soil moisture, and large-scale circulation patterns and the causes of individual drought events in Europe. However, there is still much to be understood, particularly about the climatology of the onset and termination (O&T) of droughts in this region. Therefore, here, we investigate the temporal characteristics and atmospheric drivers associated with O&T of soil moisture droughts in southern (SEU) and central Europe (CEU) on the seasonal scale during the period of 1981–2020. We also examine atmospheric mechanisms that intensify droughts from their onsets. 

Different drought indices (SPEI, surface, and root-zone soil moisture anomalies —SM) obtained from various data sources that are based on observations and land surface models (ERA5, ECAD, GLEAM-v3, and GLDAS-2) were used to calculate the duration and seasons of occurrence of O&T. The traditional clustering method, combined with the L-moment correlation analysis, were performed to detect atmospheric drivers in geopotential heights (GP) from ERA5. 

Our results show that the duration of O&T depends on the drought index: it is shorter in SPEI and surface SM but longer in deeper SM, which implies that atmospheric signals do not fully propagate to the deep soil layers. The season of occurrence of O&T depends not only on the drought index but also on the dataset and the region. The difference between the datasets is more pronounced in CEU, showing no common season of occurrence of O&T. In contrast, more O&Ts are likely to occur during the fall and winter in SEU, indicating the importance of precipitation variability during these wet seasons in initiating and terminating droughts. In terms of atmospheric drivers, frequent anticyclonic circulation patterns in central Europe linked with the northward shift and weakening of westerlies are more commonly detected during the onsets. Conversely, the opposite cyclonic circulation condition prevails during the termination periods. Strong increases in regional GP related to the initial development of dry conditions are observed during the onsets. However, during the intensification period, regional GP exhibits little variability with no statistically significant change in the mean values. Surface temperature (T) also changes little during O&T and the intensification period, which may indicate that, on a multi-seasonal time scale, the influence of temperature on droughts is less pronounced than those of the large-scale atmospheric drivers. However, the effect of T becomes significant in the summer. Anomalously high T intensifies the impacts of droughts during the warm seasons in ongoing multi-season droughts. A clear example of this is the multi-season 2015–2020 drought in CEU.

How to cite: Kim, W. M., González-Rojí, S. J., and Simpson, I.: Temporal Characteristics and Atmospheric Drivers of Onset and Termination of Soil Moisture Droughts in Europe, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-65, https://doi.org/10.5194/ems2023-65, 2023.

Onsite presentation
Anna Kis, Rita Pongrácz, and János Adolf Szabó

Changing climatic conditions affect several sectors and processes in the environment, including river discharge. It is important to estimate the probable changes, as it may play an important role in flood defence, ecosystems, transportation, energy supply or water-management. Our ultimate aim is to analyse the runoff conditions in a small European catchment, namely, the Upper-Tisza basin. As a first step of our investigation, climatic conditions are analysed for the target area.

For the analysis the observation-based CARPATCLIM dataset and 11 regional climate model simulations from the EURO-CORDEX program are used. Three 30-year-long time periods are selected (1972–2001, 2021–2050, 2069–2098) and three different scenarios (RCP2.6, RCP4.5, RCP8.5) are applied to analyse the future conditions from an immediate reduction of anthropogenic greenhouse gas emission to a later reduction, and finally no mitigation throughout the 21st century. Therefore, uncertainties emerging from both the applied model and the applied scenario can be assessed. Temperature and precipitation characteristics are calculated on a monthly basis for the entire domain, and for six hydrological stations (namely, Alsókalocsa, Bisztra, Királymező, Ökörmező, Rahó, Tiszabecs). Beside the mean values, different percentile values and climate indices are determined, e.g. the consecutive dry days, the number of precipitation days with more than 5, 10 and 20 mm, the highest one-day and five-day precipitation amount, the number of cold days and frost days.

According to our results, higher temperature values will occur in the entire area. The greatest warming in the Upper-Tisza basin is projected for January, when temperature increase can exceed 4.6 °C by the end of the 21st century according to the multi-model mean under the RCP8.5 scenario. Precipitation is projected to increase in winter, while a precipitation decrease in summer is likely to occur according to the RCP8.5 scenario. Higher temperature (which may result in less snow) and altered temporal distribution of precipitation clearly have an effect on runoff conditions, so in order to analyse them in details, the next step of our research is to run the DIWA hydrological model driven by the different climate model simulations.

How to cite: Kis, A., Pongrácz, R., and Szabó, J. A.: Analysing hydroclimatic changes in the Upper-Tisza catchment under mitigation and non-mitigation scenarios, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-208, https://doi.org/10.5194/ems2023-208, 2023.

Onsite presentation
Klaus Haslinger, Wolfgang Schöner, Jakob Abermann, Gregor Laaha, Konrad Andre, Marc Olefs, and Roland Koch

In this paper future changes of surface water availability in Austria are investigated. We use an ensemble of downscaled and bias-corrected regional climate model simulations of the EURO-CORDEX initiative under moderate mitigation (RCP4.5) and Paris agreement (RCP2.6) emission scenarios. The climatic water balance and its components (rainfall, snow melt, glacier melt and atmospheric evaporative demand) are used as indicators for surface water availability and we focus on different altitudinal classes (lowland, mountainous and high alpine) to depict a variety of processes in complex terrain. Apart from analysing the mean changes of these components we also pursue a hazard risk approach by estimating future changes in return periods of meteorological drought events of a given magnitude as observed in the reference period. The results show in general wetter conditions over the course of the 21st century over Austria on an annual basis compared to the reference period 1981-2010 (e.g. RCP4.5 +107 mm, RCP2.6 +63 mm for the period 2071-2100). Considering seasonal differences, winter and spring are getting wetter due to an increase in precipitation and a higher fraction of rainfall as a consequence of rising temperatures. In summer only little changes in the mean of the climatic water balance conditions are visible across the model ensemble (e.g. RCP4.5 ±0mm, RCP2.6 -2 mm for the period 2071-2100). On the contrary, by analysing changes in return periods of drought events, an increasing risk of moderate and extreme drought events during summer is apparent, a signal emerging within the climate system along increasing warming.

How to cite: Haslinger, K., Schöner, W., Abermann, J., Laaha, G., Andre, K., Olefs, M., and Koch, R.: Apparent contradiction in the projected climatic water balance for Austria: wetter condition on average versus higher probability of meteorological droughts, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-426, https://doi.org/10.5194/ems2023-426, 2023.

Onsite presentation
Peter C. Kalverla, Stefan Verhoeven, Bart Schilperoort, Sarah Alidoost, Yang Liu, Niels Drost, Jerom Aerts, and Rolf Hut

In our digital age, connecting models and data from various components of the earth system becomes more and more important. To this end, it is important to define standards and interfaces facilitate such integration. Here, we present the approach we took for eWaterCycle [1].

eWaterCycle is a fully Open Source system designed explicitly to advance the state of Open and FAIR hydrological modelling. It gives users access to a centralized platform where they can perform hydrological experiments. Complete with data, a suite of models, an interactive scripting environment, and a graphical explorer to quickly setup an experiment.

Hydrological models vary in programming language, their setup and configuration. They require differently defined inputs, and do not have a standard form of output. This makes it challenging to compare and exchange models and their inputs and output. eWaterCycle aims to solve this, so scientists can build upon each other’s work and focus on scientific questions instead of technical details.

Inside eWaterCycle, models are wrapped in a Basic Model Interface and live in their own isolated containers. We developed grpc4bmi  to enable communication with models inside their containers. This means that you can talk to different models, written in a range of programming languages, in a standardized way. ESMValTool is used to generate the meteorological forcing data with reproducible recipes. Discharge observations from the USGS and GRDC are available to validate the models.

The platform comes with comprehensive documentation, including a suite of example notebooks. It also includes setup instructions for system administrators and guidance for incorporating new models. The interface between meteorology and hydrology is most prominent in the forcing generation module. Beyond that, the standards and technology used for the hydrological models in eWaterCycle can be extended to other components of the land-atmosphere continuum.

[1] https://doi.org/10.5194/gmd-15-5371-2022

How to cite: Kalverla, P. C., Verhoeven, S., Schilperoort, B., Alidoost, S., Liu, Y., Drost, N., Aerts, J., and Hut, R.: eWaterCycle as a modelling interface between meteorology and hydrology, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-480, https://doi.org/10.5194/ems2023-480, 2023.

Onsite presentation
Rasmus E. Rasmus E. Benestad, Andreas Dobler, Kajsa M. Parding, Julia Lutz, Abdelkader Mezghani, Oskar Landgren, and Jan Erik Haugen

Rainfall intensity-duration-frequency (IDF) curves play an important role in water management, for instance urban stormwater handling. They are often derived by fitting generalized extreme value distributions to observed annual maximum rainfall values and require long-term observations of rainfall at sub-daily scales to get robust estimates. However, mathematical models describing the IDF curves have been observed to have a fractal dimension, providing a possibility to avoid the challenging data requirement. In this case, we used a simple analytical formulation, where two key parameters specify the shape of the curves: the wet-spell mean precipitation and frequency. These two parameters also play a role for the fractal dimension of the temporal rainfall scales. 

This study aimed to take a step towards a better understanding of which conditions may play a role for the fractal shapes and how they are affected by geographical conditions. To this end, we have explored the dependency between wet-spell mean precipitation and frequency over different timescales, using data from convective-permitting (3km) climate simulations with the regional climate model HCLIM over northern Europe. The analysis was applied to HCLIM results with boundary conditions from the ERA Interim reanalyses, as well as the EC-Earth and GFDL-CM3 global climate models.

The simulated sub-daily fractal dimensions were influenced by geographical conditions for both the wet-spell mean precipitation and the wet-spell frequency. The results were consistent for the different boundary conditions representing current climate conditions (reanalysis and GCMs) and hence independent of the driving model. Similar simulations for the future, following the RCP8.5 scenario, hinted at changes in the fractal shapes at high latitudes. However, for large regions, there was little indication of change. This study is an example of using high-resolution regional climate model data for testing hypotheses where consistent, dense and temporally high-resolved long-term observational networks are lacking.

How to cite: Rasmus E. Benestad, R. E., Dobler, A., Parding, K. M., Lutz, J., Mezghani, A., Landgren, O., and Haugen, J. E.: Temporal scaling dependency in precipitation simulated by the HCLIM regional climate model, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-543, https://doi.org/10.5194/ems2023-543, 2023.

Online presentation
Fatima Pillosu, Christel Prudhomme, and Hannah Cloke

Flash floods are one of the most devastating natural hazards. They can occur in very large or small rural or urban areas, with little to no warning. Extreme (localized) rainfall plays a crucial role.  

This presentation compares the rainfall forecast performance, for the raw ECMWF ensemble (ENS) and post-processed point-scale output derived from that (ecPoint), in pinpointing areas at risk of flash floods. Performance evaluation is based on location and timing accuracy for the flash floods. Long-term objective verification and case studies are used to compare.

Although ENS effectively identifies areas at flash flood risk in instances of large-scale rainfall, its performance falters when confronted with localized extreme convective systems. We show how ecPoint yields superior results for both scenarios, pinpointing well areas at flash flood risk up to medium-range timescales. This enables decision-makers to extend their preparedness and action time window. 

This presentation will also demonstrate forecast system strengths and weaknesses, and how forecasters can leverage these to produce better predictions of areas at flash flood risk up to medium-range lead times.

How to cite: Pillosu, F., Prudhomme, C., and Cloke, H.: Is it possible to identify flash flood risk areas with global model rainfall forecasts? A comparative study for the ECMWF ensemble - raw model versus a point-scale post-processed version., EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-611, https://doi.org/10.5194/ems2023-611, 2023.

Posters: Thu, 7 Sep, 16:00–17:15 | Poster area 'Day room'

Display time: Wed, 6 Sep 10:00–Fri, 8 Sep 13:00
Chairpersons: Timothy Hewson, Jan-Peter Schulz
Temporal relationship of solar-Induced chlorophyll fluorescence (SIF) and gross primary productivity (GPP) measured at ground to satellite scale over different ecosystems
Juan Quiros, David Herrera, Bastian Siegmann, Jean Christophe Calvet, Vera Krieger, Roel Van Hoolst, Tarek El-Madany, Mirco Migliavacca, and Uwe Rascher
Tomas Ghisi, Milan Fischer, Jana Bernsteinova, Jakub Bohuslav, Zdenek Zalud, Evzen Zeman, and Miroslav Trnka

The Thaya river basin is one of the key river basins in the southern part of the Czech Republic. Due to extensive river regulations and partial drainage of the basin area, it belongs to river basins sensitive to climate change impacts. This is supported by significant negative runoff trends over the past 40 years. The main aim of this contribution is to analyze impacts of the hypothetical land use changes on the hydrological processes of the upper Thaya basin. In this study, we used a hydrological Mike SHE model. The physically based and spatially distributed model Mike SHE was calibrated and validated using measured river discharge data in the three hydrological profiles for the period 1991–2020. Selected hypothetical adaptation land use scenarios including the vegetation cover changes were compared to the reference scenario (represents the current land use of the basin) to analyze the impacts of the simulated land use changes on the hydrological processes in the basin. Except the field management changes, the land use scenarios encompassed extreme vegetation changes, where the entire basin in the model was changed to (1) grassland, (2) mixed deciduous-coniferous forest, (3) deciduous forest, or (4) cropland. These extreme land use scenarios were analyzed for several CMIP6 downscaled climate models and different RCP emissions scenarios up to the end of the first half of the 21st century. The results showed that the evapotranspiration is the dominant water loss component for all simulated land use scenarios in the basin. The highest evapotranspiration was modeled for the mixed deciduous-coniferous forest, while the lowest was for the grassland and cropland scenarios. The Mike SHE model also simulated that the total runoff was lowest for both forest scenarios. Results of the study showed the sensitivity of the river basin on the climate change impacts, where a slight increase of the evapotranspiration value in the basin has a significant effect on the total runoff from the basin. This study was conducted within the evaluating and designing nature-based adaptation measures to climate change in the Thaya river basin.

How to cite: Ghisi, T., Fischer, M., Bernsteinova, J., Bohuslav, J., Zalud, Z., Zeman, E., and Trnka, M.: The impact of land use scenarios on the water balance in the Thaya river basin, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-276, https://doi.org/10.5194/ems2023-276, 2023.

Matthew Newell, Martin Drews, Mark Payne, and Morten Larsen

Climate projections indicate a general increase in precipitation in Northern Europe accompanied by an increase in variability across a range of hydroclimate variables. In Denmark, increases in the amount of winter precipitation have resulted in several winter seasons (e.g., 2019-2020 and 2022-2023) with above-average precipitation. As a result, these periods have been marked by a vast extent of surface flooding due to the successive nature of precipitation events. Recent occurrences of drought (2018 and 2022) in Denmark, which have historically been less of a concern, have reduced water availability and resulted in impacts across sectors, with particularly large impacts on agricultural systems. The intra- and/or inter-annual occurrence of wintertime compound precipitation events and summertime flash drought events may emerge as an important constraint on agricultural productivity in Denmark. This analysis uses the Standardized Antecedent Precipitation-Evapotranspiration Index (SAPEI) to quantify periods of excess rainfall and precipitation deficits. The SAPEI can capture both periods of excess soil moisture (due to preconditioning by successive storms) and soil moisture deficits since it serves as a proxy for soil moisture. In the study, SAPEI is applied to observational records and climate projections to assess changes in the frequency of hydrometeorologic events, and to localize areas, which are specifically at risk to these extremes under current and future climates. Recent events are highlighted within the context of natural climate variability. These events are detailed to illuminate the impacts of compound wet and dry events and illustrate their importance as an important compound event in need of further research. 

How to cite: Newell, M., Drews, M., Payne, M., and Larsen, M.: Compound hydrometeorologic extremes in Northern Europe: a case study on flooding and drought in Denmark, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-241, https://doi.org/10.5194/ems2023-241, 2023.